This invention relates to a duplex lock codable by a master key and releasable by a duplex key.
The problem of providing a safety lock has given rise to a great number of solutions working on various principles and all aiming at increasing security and efficiency of the lock. Also the Applicant of the present application has already made a prior invention on which U.S. Pat. No. 3,726,116 has been issued on Apr. 10, 1973 and which relates to a safety lock similar to the one to be described hereinafter, in which the locking elements are fixed in helical springs. The lock described in Applicant's aforementioned prior patent and other similar locks have the drawback that they have to be readjusted when the balanced operation of the moving parts is impaired by wear of cooperating members and use of the lock. Further, such readjustment must be precise and accurate.
It is an object of the present invention to overcome these drawbacks by providing a lock that does not require any such readjustment and affords a great variety and ease of coding together with a high degree of security of operation.